LO 
CO 


o 


\ 


DIVERSITY 

- 


Rainfall      in 

MEXICO 


Romulo  Escobar 

Ex-Chief  of  the  Depart- 
ment of  Agriculture 
and  Forestry 


Mexican  national  Commission 

Universal  Exposition,  St.  Louis,  J904 


>. 


Rainfall      in 

MEXICO 


Romwlo  Escobar 

Ex-Chief  of  the  Depart- 
ment of  Agriculture 
and  Forestry 


Mexican  national  Commission 

Universal  Exposition,  St.  Louis,  J904 


The 

Whitc-Erans- 
f  enfold  Company 
In  Buffalo,  New  York 


RAINFALL    IN    MEXICO 


HEN  one  has  the  opportunity  of  hear- 
ing the  general  opinion  of  Mexican 
farmers  relative  to  the  system  of 
our  rainfall,  the  uniformity  of  such 
opinion  is  somewhat  astonishing,  inasmuch  as  they 
all  claim  an  unfavorable  change,  more  and  more 
noticeable  every  year,  in  said  system,  not  only 
because  of  the  terrible  decrease  of  the  annual  preci- 
pitation, but  also  of  the  retardation  and  growing 
irregularity  of  the  rainy  season.  It  will  not  be 
necessary  to  travel  extensively  over  the  Republic  to 
be  convinced  that  the  above  mentioned  belief  is  as 
general  over  the  frontier  states  as  it  is  in  those  of 
the  southern  portions  of  the  country. 

I  have  been  fully  convinced  of  the  generality 
of  such  belief  by  means  of  certain  interrogatories 
relating  to  the  groups  I  have  under  my  charge  as 
member  of  the  Mexican  Commission  to  the  Saint 
Louis  World's  Fair,  as  one  of  the  questions  put  in 
said  interrogatories,  relating  to  the  local  difficulties 
hampering  the  progress  of  agriculture,  has  been 
answered  from  all  parts  of  the  Republic,  stating  that 
one  of  the  principal  difficulties  is  the  scarcity  and 
irregularity  of  rainfall,  which  is  more  and  more 
marked  every  year. 

And  this  opinion  prevails  not  only  in  the 
Republic ;  an  agent  of  the  Department  of  Agricul- 
ture of  the  United  States  predicted  for  us,  a  few 


RAINFALL         IN          MEXICO 

years  ago,  a  complete  ruin  on  account  of  the  de- 
crease of  our  rainfall,  and,  Doctor  Moises  S.  Bertoni, 
Director  of  the  School  of  Agriculture,  at  Asuncion, 
Paraguay,  in  speaking  of  rainfall  in  Mexico,  he 
states  that  he  has  been  able  to  discover  a  decrease, 
similar  to  the  one  we  have  suffered,  over  the  basin 
of  the  Paraguay  River,  and  he  affirms  that  the  same 
thing  has  happened  in  Argentine,  Brazil,  and  in 
general,  all  over  Latin  America. 

As  the  conclusions  I  may  arrive  at  in  the 
course  of  this  study  might  be  influenced,  contrary 
to  my  desire,  by  the  prejudices  I  may  have  before 
going  into  the  matter,  I  must  confess  that  I  have 
never  been  of  the  opinion  that  the  decrease  of  our 
rainfall  has  been  so  remarkable  and  general  as  it  is 
claimed,  because,  in  the  absence  of  data  secured  by 
pluviometric  observations,  which  would  be  the  only 
reliable  foundation  we  could  find,  I  have  been  un- 
able to  observe  so  marked  a  change  as  is  generally 
admitted. 

I  have  noticed  very  brusque  changes  indeed, 
series  of  years  of  real  drouth,  but  the  same  have 
never  been  permanent.  I  have  seen  that  many  lakes 
situated  along  the  sides  of  the  various  railway  lines 
I  have  been  over  during  many  years,  such  as  the 
lakes  Encinillas  and  Patos,  a  short  distance  from  the 
line  of  the  Mexican  Central  Railway,  built  in  1 88 1 , 
have  for  many  years  occupied  a  greatly  reduced 
surface,  and  that  the  last  mentioned  lake  has  in 
some  instances  disappeared  completely  ;  but  at  other 


RAINFALL          IN          MEXICO 

times  I  have  seen  both  lakes  with  as  much  water  as 
they  ever  had  since  the  first  time  I  saw  them. 
Lake  Patos,  for  instance,  only  a  few  years  ago, 
reached  a  maximum  capacity  never  before  recorded 
even  by  the  oldest  inhabitants  of  the  adjacent  dis- 
tricts. I  have  been  unable  to  notice  any  visible 
change  in  many  of  the  streams  I  have  known  from 
childhood;  I  have  heard,  however,  of  rivers  which 
have  entirely  disappeared,  but  on  the  other  hand,  I 
have  seen  new  ones  come  into  existence,  and  when- 
ever the  former  occurrence  has  happened,  the  same 
has  been  the  result  of  the  felling  of  forests  located 
in  the  upper  hydrographical  slopes,  or  because  a 
current  of  extraordinary  force  has  swept  away  from 
creeks  and  ravines  their  alluvial  deposits,  thus 
diminishing  their  means  to  arrest  the  flow  of  rain 
water,  which  in  former  times  used  to  settle  in  their 
basins,  and  facilitating  the  drainage  of  the  same. 

The  belief  that  the  railways  have  been  instru- 
mental in  bringing  about  the  decrease  of  rainfall, 
not  because  of  the  forests  destroyed  on  their  ac- 
count, but  due  to  the  strange  relations  attributed  to 
them,  probably  because  their  construction  coincided 
with  a  period  of  decrease  in  our  annual  precipita- 
tion, has  always  appeared  to  me  as  unfounded,  and 
the  only  reason  why  I  mention  it  is  because  of  its 
universality,  though  I  consider  the  same  unworthy 
of  comment 

The  belief  which  attributes  such  marked 
changes  to  the  felling  of  forests  does  not  appeal  to 


RAINFALL         IN          MEXICO 

me  as  unreasonable,  but  I  do  think  that  its  influ- 
ence has  been  somewhat  exaggerated,  since  I  have 
heard  such  complaints  not  only  in  places  where 
forests  have  been  destroyed,  but  also  in  settlements 
far  away  from  any  line  of  communication  that  could 
cause  an  extensive  felling  of  the  forests,  and  because 
I  have  noticed  that  said  changes  are  claimed  in 
communities  whose  dominating  winds  during  the 
rainy  season  do  not  come  from  the  quadrant  where 
the  forests  have  been  felled,  and,  even  admitting 
that  the  above  influence  could  be  of  a  more  local 
character  than  what  would  be  proper  to  believe,  it 
has  been  demonstrated  that  the  effect  claimed  is 
caused  by  an  extensive  felling  of  the  forests  in  the 
direction  towards  which  the  dominating  winds  will 
blow. 

The  opinion  of  the  Baron  of  Humboldt  and  of 
the  wise  Agriculturist  Boussignault,  the  distinguished 
travelers  who  visited  and  studied  our  country,  can- 
not be  disputed,  as  it  is  an  established  fact  that  the 
extensive  destruction  of  the  forests  brings  about  the 
most  lamentable  results,  especially  so  in  regard  to 
the  life  of  spring  waters  in  the  lowlands,  but  I  do 
believe  that  the  above  opinion  has  been  accepted 
with  increased  significence  as  a  basis  to  prove  the 
decrease  of  our  rainfall. 

I  am  of  the  opinion,  besides,  that  the  question 
of  rainfall,  like  many  others,  has  been  made  the 
subject  of  superstition.  Persons  of  superstitious  in- 
clinations always  remember  the  times  when  their 


RAINFALL         IN          MEXICO 

omens  have  turned  into  reality,  but  they  forget  the 
many  instances  when  they  have  erred.  Such  is  the 
case  with  us,  we  keep  fresh  in  our  memory  the 
years  of  heavier  rains  we  have  seen  from  childhood 
and  in  speaking  of  them  in  times  of  drouth  we  will 
surely  come  to  the  conclusion  that  our  supply  of 
rainfall  has  decreased.  Ever  since  I  have  been  able 
to  remember,  I  have  heard  people  complain  of  the 
want  of  rain  and  often  have  heard  the  statement : 
"This  is  the  worst  drouth  we  have  ever  experienced." 
On  the  other  hand,  I  have  never  heard  any  comment 
at  all  in  normal  or  good  years ;  it  seems  as  if  the 
latter,  being  considered  exceptional,  does  not  de- 
serve any  mention. 

As  persons  of  an  advanced  age  unanimously 
confirm  this  fact,  I  have  been  led  to  believe  that 
the  change  in  our  system  of  rainfall  would  ap- 
pear more  marked  if  a  long  period  of  time  would 
be  subjected  to  comparison,  instead  of  considering 
only  the  last  third  part  of  the  nineteenth  century. 

The  opening  of  new  waterworks,  canals,  etc., 
are  a  more  frequent  cause  than  in  the  past  for  the 
exhaustion  of  rivers  and  rivulets ;  they  hamper  the 
facilities  for  irrigating  the  lower  lands,  and  people 
who  notice  the  decrease  in  the  volume  of  water  of  a 
river,  which  never  may  have  been  known  to  become 
dry,  or  those  who  experience  the  loss  of  crops  where 
they  have  been  abundant  in  the  past,  without  know- 
ing or  even  considering  the  direct  cause  of  such 
phenomena,  are  prone  to  declare  that  never  before 


RAINFALL         IN          MEXICO 

have  they  seen  such  scarcity  of  water,  and  thus,  the 
above  mentioned  idea  assumes  the  proportions  of  a 
general  belief. 

I  have  gone  as  far  as  to  imagine  that  said 
belief  might  in  some  way  effect  the  question  of 
laborers  for  agricultural  purposes.  Il  is  a  known 
fact  that  laborers  are  getting  to  be  more  and  more 
scarce  every  day  in  the  farming  industries,  not  only 
on  account  of  the  reconcentration  of  the  rural  popu- 
lation in  the  cities  and  towns,  but  also  on  account 
of  an  increase  of  the  other  classes  of  work,  develop- 
ing even  in  the  farming  districts.  There  are  many 
at  present  which  have  been  completely  abandoned, 
owing  to  the  fact  that  many  enterprises  of  a  paying 
character  in  the  past  would  be  a  dead  loss  at  pres- 
ent ;  and  because  the  construction  of  new  railway 
lines,  modern  factories  and  the  operation  of  new 
mines,  take  a  large  number  of  laborers  away  from 
agricultural  pursuits.  Farmers  who  generally  culti- 
vate an  extensive  system  of  lands,  are  at  present 
unable  to  secure  the  number  of  laborers  they  could 
find  in  former  times,  they,  however,  insist  upon 
planting  the  same  area  of  land  and  even  clear  new 
plots,  which  they  are  incapable  of  treating  as  often 
and  cultivating  under  the  laborious  rules  of  agricul- 
ture practiced  fifteen  or  twenty  years  ago.  More- 
over, experience  has  demonstrated  beyond  doubt 
that  cultivation  means  economy  of  water,  that  a  deep 
preparation  of  the  soil  before  planting  or  the  treat- 
ing of  a  field  after  irrigation  or  rain  have  taken 


RAINFALL          IN          MEXICO 

place,  enables  the  soil  to  absorb  a  greater  amount  of 
water  and  to  maintain  the  moisture  it  may  have  for 
a  longer  period  of  time.  There  is  enough  truth  in 
the  above  to  authorize  the  statement  that  the  culti- 
vation of  the  soil  is  equivalent  to  its  irrigation.  If 
the  work  of  cultivating  the  soil  is  attended  with 
many  difficulties,  if  the  same  is  effected  in  a  defici- 
ent manner,  the  results  are  bound  to  be  equal  to 
those  experienced  on  account  of "  the  scarcity  of 
water. 

May  we  not  presume  that  the  labor  question, 
owing  to  the  conditions  mentioned,  is  to  a  certain 
extent  responsible  for  the  belief  that  our  system  of 
rainfall  has  enormously  decreased  ? 

Laboring  under  these  ideas  I  have  commenced 
my  study,  drafting  diagrams  showing  the  precipita- 
tion in  each  of  the  places  where  there  is  a  meteoro- 
logical observatory,  and  from  which  I  have  been 
able  to  secure  the  data  corresponding  to  a  period  of 
not  less  than  six  years,  such  being  the  minimum 
time  I  have  adopted  to  consider  the  changes  that 
may  have  occurred  in  their  system  of  rainfall.  For 
localities  which  have  furnished  me  with  a  statement 
of  their  monthly  precipitation,  I  have  drawn  annual 
curves  to  the  end  of  discovering  whether  there  has 
been  any  delay  or  increase  in  the  irregularity  of  their 
rainfall.  These  diagrams  have  been  drawn  by  tak- 
ing a  line  to  represent  the  average  annual  precipita- 
tion admitted  by  me,  in  a  period  subsequent  to  1877, 
and  marking  on  said  line  the  abscissas  representing 


RAINFALL          IN          MEXICO 

the  periods  of  time,  the  years  and  months,  I  have 
drawn  those  which  appear  above  or  below  the  line, 
as  the  case  may  be,  to  show  the  increase  or  decrease 
over  or  below  the  normal  precipitation  of  each 
year. 

I  will  treat  the  diagram  of  each  locality  sepa- 
rately, and  I  will  afterwards  make  an  abstract  or 
recapitulation  to  enable  me  to  establish  deductions 
of  a  general  character,  in  connection  with  which  I 
will  endeavor  to  set  aside  my  personal  views  in  the 
matter,  bearing  only  upon  the  results  shown  by 
the  recapitulation. 

It  is  to  be  regretted  that  we  have  not  a  more 
extensive  meteorological  system,  and  that  there  are 
but  limited  observations,  prior  to  1877 ;  but  in 
spite  of  this  fact,  these  studies  must  be  carried 
forward  with  the  idea  that,  though  the  data  at  our 
disposal  are  insufficient,  and  that  we  are  in  danger 
of  erring  in  our  deductions,  and  even  though  we 
may  leave  many  blank  spaces  in  our  work,  since  it 
is  impossible  to  do  everything  at  one  time,  we  will, 
however,  accomplish  one  material  advantage,  /.  e., 
the  work  of  compilation. 

Many  indeed  have  been  the  hardships  attend- 
ing the  work  of  collecting  what  few  data  I  have 
slowly  gathered,  though  I  have  been  honored  with 
the  kind  co-operation  of  some  disinterested  man- 
agers of  observatories,  whose  names  I  will  mention 
in  each  case  and  for  which  I  feel  sincerely  thankful, 
and  I  trust  that  my  present  work  will  save  this 


RAINFALL          IN          MEXICO 

troublesome  task  to  those  who,  possessing  more 
knowledge  and  better  elements,  may  in  the*  future 
undertake  a  vaster  study  of  a  question  which  so 
deeply  affects  our  country. 

I  have  no  doubt  that  the  conclusions  arising 
from  my  study  may  be  in  conflict  with  the  individual 
opinion  of  many  others,  since  the  former  will  refer 
to  a  matter  where  most  people  generally  follow  their 
own  beliefs,  it  being  impossible  to  destroy  the  value 
of  the  weak  or  strong  arguments  upon  which  they 
base  the  same ;  however,  I  hold  that  no  argument 
can  logically  give  better  support  to  my  deductions 
than  the  proofs  rendered  by  pluviometric  records, 
therefore,  I  shall  use  the  latter  for  my  guidance. 
Moreover,  the  fact  of  the  meteorological  observa- 
tories being  located  in  populated  centers,  will  natu- 
rally show  greater  changes  than  those  claimed  in  the 
rural  districts,  provided  we  admit  as  true  that  the 
felling  of  the  forests  has  had  so  great  influences  in 
the  matter  as  are  attributed  to  it,  it  being  proper  to 
assume  that  all  the  observatories  we  have  are  situ- 
ated in  the  heart  of  districts  where  the  destruction 
of  the  forests  has  been  more  extensive. 

Being  convinced  of  the  advantages  gained  by 
making  a  separate  study  of  the  changes  of  the  pre- 
cipitation of  rainfall  in  the  different  zones  of  the 
Republic,  as  the  number  of  observatories  are  limited 
and  the  same  are  irregularly  distributed  over  the 
nation's  territory,  I  have  preferred  to  study  the  pre- 
cipitation in  the  same  order  in  which  I  made  out  the 


R    A    I    N    F   A    LL         IN          MEXICO 

diagrams  without  considering  the  geographical  loca- 
tion of  the  observatories. 

When  mentioning  the  data  furnished  by  each 
observatory,  I  will  refer,  by  way  of  information,  to 
several  other  data  taken  principally  from  an  article 
published  by  Engineer  Guillermo  B.  y  Puga,  and 
from  a  book  called  "  Geographical  and  Statistical 
Notes  on  Mexico",  written  by  Licentiate  Matias 
Romero,  in  which  book  I  have  found  many  interest- 
ing data  for  this  study.  I  have  also  compared  many 
of  the  data  mentioned  herein  with  those  contained 
in  a  small  but  important  book  called  "  El  Clima  de 
Mexico",  written  by  Mr.  Manuel  Moreno  y  Anda 
(see  enclosure  No.  i ). 


RAINFALL 


I    N 


MEXICO 


Yuma,  Arizona,  U.  S.  of  A. 

DATA 

Altitude  above  sea  level  43  m. 

Average  annual  precipitation  78  mm. 

Number  of  years  recorded  28  years 

Annual  Precipitation  (C.  M.  O.) 


Puga 


1878 

73-!+ 

1879 

83.6+ 

1880 

18.8— 

1881 

24.9— 

1882 

45.2— 

1883 

59-7— 

1884 

148.8+ 

1885 

69.1- 

1886 

135-9+ 

1887 

99.1+ 

1888 

74-9+ 

1890 

1891 

67.8— 

1892 

85-1+ 

1893 

85.6+ 

1894 

74-9+ 

1895 

33-8- 

1896 

64.8— 

1897 

106.2+ 

1898 

58.7- 

1899 

15.2— 

1900 

21.6— 

1889      119.1+ 

Accepted  average  annual  precipitation         71  mm.  i 
Number  of  years  22 

The  above  data,  though  taken  from  observa- 
tions made  abroad,  are  similar  to  the  ones  that 
could  be  obtained  in  the  northwestern  region  of  the 
State  of  Sonora  and  northeast  of  lower  California. 

The  smallness  of  the  precipitation  is  remark- 
able. In  none  of  our  observatories  have  we  re- 
corded such  low  precipitation. 

From  1880  to  1883,  inclusive,  the  curve  of  pre- 
cipitation shows  a  decrease  below  the  line  represent- 
ing the  average  annual  precipitation.  After  1894 
the  curve  comes  down  again  and  there  is  only  one 
year,  that  of  1897,  which  shows  an  increase  over  the 
average  precipitation. 


RAINFALL          IN          MEXICO 


El  Paso,  Texas,  U.  S.  of  A. 

DATA 

Altitude  above  sea  level  i»2O5  m.  Puga 

Average  annual  precipitation  334  mm.         " 
Number  of  years  6  " 

Annual  Precipitation  (C.  M.  O.) 

1879  168.4—       1889  180.3— 

1880  365.0+       1890 

1881  461.5+         1891    56.4— 

1882  2IO.I  +  1892  135.1  — 

1883  328.2+  1893  276.3+ 

1884  464.8+  1894  107.7 — 

1885  185.7 —  1895  259.1  + 

1886  204.7—  1896  248.7  + 

1887  248.7+  I897  315.2  + 

1888  248.7+  1898  156.5— 

1889  185.4 —  1900  201.9 — 

Accepted  average  annual  precipitation       234  mm.  8 
Number  of  years  21 

Rainfall  at  El  Paso,  Texas,  recorded  during 
this  period  of  time,  serves  the  purposes  of  this  study 
as  data  relating  to  the  northern  portion  of  the  State 
of  Chihuahua  owing  to  the  proximity  of  the  latter 
state  to  the  boundary  line. 

From  1885  to  1894  there  are  only  two  years 
over  the  average  precipitation,  1888  and  1893. 
From  1895  there  is  a  series  of  three  years  over  the 
average  precipitation,  and  from  the  latter  date  the 
curve  shows  a  decrease  covering  the  other  three 
years.  I  have  been  unable  to  secure  any  later  data 
to  1900,  but  I  am  of  the  opinion  there  must  be  an 

16 


RAINFALL          IN          MEXICO 

increase,  as  the  last  two  years,  especially  the  present 
one,  have  been  favorable  in  this  respect. 

The  mere  inspection  of  this  diagram  shows  a 
decrease  in  the  amount  of  annual  rainfall. 


RAINFALL          IN          MEXICO 

Galveston,  Texas,  U.  S.  of  A. 

DATA 

Altitude  above  sea  level  12  m.  Puga 

Average  annual  precipitation  1328  mm.        " 

Number  of  years  13                " 

Annual  Precipitation  (C.  M.  O.) 

1878  1546.9+        1889   953-0— 

1879  683.3—         l89° 

1880  1294.6+         1891  1054.3— 

1881  1353.3+         l892   629.4— 

1882  1465.1+         1893   899.9— 

1883  790.2—         1894  1032.3— 

1884  1526.0+         1895   988.3— 

1885  1589.0+         1896   602.2— 

1886  977-9—         1897   742.7— 

1887  1103.1—         1898  1066.8— 

1888  1526.2+         1899  1060.7— 

1900     17694+ 

Accepted  average  annual  precipitation      1120  mm.  6 
Number  of  years  22 

Data  relative  to  Galveston  can  be  compared 
with  those  of  several  points  of  our  Mexican  gulf  zone. 

From  1889  to  1899  the  precipitation  appears 
below  the  accepted  average,  and  during  that  period 
there  might  be  an  increase  only  in  1890,  for  which 
year  I  could  not  secure  any  data. 

The  inspection  of  this  diagram  shows  a  decrease 
in  rainfall,  though  at  the  present  time  the  same 
seems  to  be  increasing. 

18 


RAINFALL 


I    N 


MEXICO 


Zacatecas,  Zacatecas,  Mexico 


DATA 

Altitude  above  sea  level 

Annual  average  precipitation 

Number  of  years  considered 

Northern  latitude 

Average  barometric  pressure 

Maximum  temperature 

Minimum  " 

Medium 

Prevailing  direction  of  the  clouds 

"  "        "     "     wind 

Number  of  years 


2496  m.  Puga 

819  mm.  " 

10  " 

22°  46' — Matias  Romero 
573  mm.  4 
21°  8' 
6°  i' 

I3°  2' 

S.  E.          "  « 

S.  E.          "  " 

10          "  " 


Annual  Precipitation 

(J.  A  y  Bonilla  and  C.  M.  O.) 


1874  900.0+ 

1875  844.0+ 

1876  687.0+ 
1877 

1878  560.0— 

1879  672.0+ 

1880  690.0+ 

1 88 1  700.0+ 

1882  717.0+ 

1883  825.0+ 

1884  990.0+ 

1885  981.0+ 

1886  798.0+ 

1887  978.0+ 


412.0 — 
226.0 — 


1 888  1446.8+ 

1889  562.9— 

1890  658.6+ 
1891 

1892 

1893  I63-o — 

1894  368.9— 

1895  271.8 — 

1896  480.6— 

1897  784.9+ 

1898  516.0— 

1899  409.0— 

1900  805.3+ 

1901  452-9— 


Accepted  average  annual  precipitation       652  mm.  o 
Number  of  years  24 


R    A    I    N    F    ALL          IN          MEXICO 

The  diagram  for  Zacatecas  is  one  of  the  most 
interesting  among  all  those  I  have  prepared,  because 
in  the  majority  of  the  latter  years  of  heavy  rainfall 
alternate  with  those  of  low  precipitation,  thus  caus- 
ing the  curve  to  go  up  and  down  within  short  dis- 
tances, while  in  the  former  diagram  a  constant 
increase  is  shown  since  1878  to  1888,  the  decrease 
from  1885  to  1887  being  insignificant. 

From  1889  to  1897  there  is  a  curve  beneath 
the  average  line,  this  latter  year  being,  among  those 
of  the  above  period,  the  only  one  showing  a  marked 
increase  over  the  normal  precipitation. 

After  1898  the  diagram  continues  to  show  sev- 
eral irregularities  similar  to  those  of  other  localities. 

Reference  to  the  diagram  will  show  a  decrease 
in  rainfall,  though,  like  Galveston,  there  is  an  appar- 
ent tendency  to  increase. 

The  curves  for  monthly  precipitation  I  have 
drawn  for  1894  to  1901  demonstrate  a  marked 
irregularity,  the  year  1895  being  remarkable  owing 
to  the  low  precipitation  during  the  regular  rainy 
season. 


RAINFALL         IN         MEXICO 

Guadalajara,  Jalisco,  Mexico 

DATA 

Altitude  above  sea  level  1 566  m.  Puga 

Average  precipitation  864  mm.  " 

Number  of  years  6  " 

Northern  latitude  20°  41'  M.  R. 

Average  barometric  pressure  636  mm.  2  4t 

Maximum  temperature  35°  5'  " 

Minimum  "  4°  5'  " 

Medium  temperature  19°  7'  " 

Average  annual  precipitation  86 1  mm.  9  " 

Number  of  years  7  " 

Annual  Precipitation 

(M.  Ni«to  C.  M.  O.  and  Belem  Hospital) 

As  in  the  data  secured  from  Guadalajara  there 
are  several  differences,  I  have  in  some  cases  taken 
the  averages  between  the  data  furnished  by  the 
Director  of  the  Guadalajara  Observatory  and  those 
secured  from  the  C.  M.  O.,  relating  to  the  latter  as 
well  as  to  the  Betem  Hospital  Observatory, 


1  874 

900.0  — 

1888 

991.0— 

1875 

844.0- 

1889 

792.0  pr. 

2- 

1876 

687.0— 

1890 

1076.9  " 

3- 

1877 

830.0— 

1891 

1087.1  " 

3 

1878 

1083.0  — 

1892 

789.7  » 

2- 

1879 

670.0  — 

1893 

728,9  « 

2- 

1880 

1092.0  — 

1894 

2003.8  " 

2 

1881 

1032.8  per  2  — 

1895 

2488.6  " 

2 

1882 

828.0  "  " 

1896 

1426.7  " 

2 

1883 

719.2  -  •« 

1897 

1340.7  " 

3 

R    A 

I    N    F    A    L    L 

IN         MEXICO 

1884      605.4— 
1885     "43-°+ 
1886      853.9 
1887     1013.4— 

1898      1875.8  pr.  2+ 
1899     J432-3   "    2+ 
1900 
1901     1323.9+ 

Accepted  average  aunual  precipitation      1134  mm.  5 
Number  of  years  24 

The  most  remarkable  feature  of  the  diagram 
corresponding  to  Guadalajara  is,  that  prior  to  1894 
all  years  show  a  precipitation  inferior  to  the  normal 
average,  with  the  exception  of  1885,  which  .shows  a 
slight  increase,  but  after  1894  all  years  had  more 
than  the  normal  rainfall,  a  rather  curious  circum- 
stance, which  would  at  least  indicate  an  ameliora- 
tion in  the  system  of  rainfall  in  that  city. 

The  inspection  of  the  diagram  demonstrates  an 
increase  of  rainfall. 

In  the  curves  for  monthly  precipitation  I  have 
made  up  with  data  relating  to  years  subsequent  to 
1889,  furnished  by  Mr.  Mariano  Nieto  of  the  State 
Observatory,  It  may  be  seen  that  the  curve  begins 
to  rise  in  every  case  either  in  May  or  June,  that  is 
to  say,  that  the  rainy  season  begins  at  such  time. 
It  also  shows  that  the  rainy  season  is  well  defined. 
As  the  curve  will  not  come  down  again  until  one  of 
the  last  three  months  of  the  year,  generally  October, 
and  that  the  month  of  April  is  one  of  the  dryest 
months  all  through,  as  it  only  had  a  precipitation 
worthy  of  note,  /.  e.,  125  mm.,  in  1896,  the  same 
being  either  nothing  at  all  or  very  insignificant  in  all 
other  years. 


RAINFALL         IN         MEXICO 


Saltillo,  Coahuila,  Mexico 
DATA 

Altitude  above  sea  level  1632  m.  Puga 

Average  annual  precipitation  554  mm.  " 

Number  of  years  3 

Northern  latitude  25°  25'  M.  R- 

Medium  pressure                                    632  mm  I  " 

Maximum  temperature  34°  o'  " 

Minimum            «  2°  8'  « 

Medium               «  16°  8' 

Average  annual  precipitation  527.3  " 

Number  of  years  4  ** 

Annual  Precipitation 

(M.  Kubicza,  Manager  of  the  Observatory  of  the  College 
of  San  Juan  Nepomuceno) 

1885  506.5—         1-894  815.5+ 

1886  493.6 —        1895  596.0+ 

1887  674.4+        1896  713-°+ 

1888  639.9+         1897  34*3-0— 

1889  776.0+         1898  405.0 — 

1890  585.6+         1899  553-8+ 

1891  3I3-°—         I9°°  74L5+ 

1892  777-9+         J90!  164,3— 

1893  3°7-4— 

Accepted  average  annual  precipitation       553  mm.  3 
Number  of  years  17 

The  only  thing  worthy  of  note  that  I  find  in 
Saltillo's  diagram  is  the  uniform  increase  of  annual 
precipitation  since  1897  until  1900,  and  the  consid- 
erable decrease,  which  is   the   lowest  one   in   the 
23 


RAINFALL          IN          MEXICO 

period  of  time  registered,  corresponding  to  1901. 
On  the  other  hand,  the  irregularities  shown  in  the 
diagram  are  in  proportion  to  the  precipitation  and 
are  not  so  remarkable  as  those  in  other  observa- 
tories. 

The  inspection  of  the  diagram  does  not  seem 
to  demonstrate  either  an  increase  or  a  decrease, 
although  the  last  year  shows  a  marked  decrease  of 
rainfall. 

The  curves  for  monthly  precipitation  show  the 
following  features :  Great  irregularity  between  one 
year  and  the  others ;  the  unsettled  and  variable 
character  of  the  rainy  season ;  the  irregularity  of 
precipitation  in  the  months  of  July  and  August,  in 
which  the  amount  of  rainfall  has  been  sometimes 
very  heavy,  and  rather  insignificant  in  other  years. 
If  a  curve  be  drawn  to  represent  the  normal  year  to 
compare  the  same  by  superposition  with  that  of 
every  year,,  very  remarkable  differences  would  be 
found  in  every  one  of  the  years  registered. 


RAINFALL         IN         MEXICO 

Leon,  Guanajuato,  Mexico 

DATA 

Altitude  above  sea  level  1798111.      Leal     Puga 

Average  annual  precipitation  728  mm.      "           " 

Number  of  years  lo              "           •' 

Northern  latitude  21°  f                     M.  R. 

Medium  barometric  pressure  617.4 

Maximum  temperature  36°  6' 

Minimum            "  —  1°  i' 

Medium               "  18°  9' 
Prevailing  direction  of  the  clouds        S.  W. 
"      winds  N.    N.  W. 

Average  annual  precipitation  729.8 

Number  of  years  14 

Annual  Precipitation 

and  Number  of  Rainy  Days 

(Mariano  Leal) 


i878 

601.5  —  92 

1890 

867.2+145+ 

1879 

709.2+100  — 

1891 

429.8  —  116— 

1880 

825.4+119+ 

1892 

473.2—129+ 

1881 

629.9—127  + 

i893 

648.5+109— 

1882 

699-3+  ii  7— 

1894 

552.7—125+ 

1883 

900.9+134+ 

1895 

531.3  —  113— 

1884 

613.1  —  in  — 

1896 

314.6—117— 

1885 

786.2+'i3°+ 

1897 

571.7  —  118  normal 

1886 

725.9+  97— 

1898 

747.6+102—. 

1887 

781  8+136+ 

1899 

510.3  —  1  08— 

1888 

869.6+152+ 

1900 

560.6—127+ 

1889 

767-5+!34+ 

1901 

439-5—  94— 

Accepted  average  annual  precipitation  648  mm.  2 

Average  number  of  rainy  days  per  annum  1  18 

Number  of  years  24 
25 


R    A    1    N    F   A    L    L         IN          MEXICO 

The  diagram  showing  Leon's  annual  precipita- 
tion has  the  following  notable  features  worthy  of 
mention:  First. —  A  series  of  successive  years 
above  the  aveiage  precipitation,  running  from  1885 
to  1890,  inclusive.  Second.— That  in  years  prior  to 
1890  the  majority  of  years  recorded  are  above  the 
normal  line,  there  being  only  three  with  a  lower  pre- 
cipitation, i.  e.,  1878,  1881  and  1884,  while  after  the 
above  mentioned  year  (1890)  almost  all  have  had  a 
very  limited  precipitation,  as  there  is  only  one  year 
with  normal  precipitation,  1893,  and  another  one 
with  a  higher  precipitation,  1898. 

The  mere  inspection  of  this  diagram  demon- 
strates a  decrease  of  rainfall,  and  the  part  corre- 
sponding to  the  later  years  is  also  descending,  which 
fact  does  not  occur  with  other  diagrams  I  have 
studied. 

I  believe  the  latter  diagram  can  be  mentioned 
as  the  one  which  better  characterizes  a  period  of 
drouth  shown  in  the  last  decade  of  several  other 
observatories,  whose  data  I  have  studied  and  will 
mention  hereinafter. 

In  reference  to  the  above  observatory,  which  is 
one  of  the  most  important  in  the  country,  from  an 
agricultural  point  of  view,  the  data  relating  to  the 
same  having  been  furnished  me  by  its  manager,  I 
have  made  up  a  diagram  showing  the  number  of 
rainy  days  it  had  since  1878,  and  I  note  that  the 
line  follows  a  regular  course,  to  a  certain  extent,  in 
accord  with  the  line  of  precipitation  in  the  majority 


RAINFALL         IN         MEXICO 

of  years,  although  the  same  thing  does  not  occur  in 
others,  such  as  1881,  1893,  1894,  1896,  1898,  and 
1899. 

The  curves  of  monthly  precipitation  do  not 
appear  so  irregular  as  they  do  in  other  observa- 
tories, but  they  are,  however,  more  irregular  than 
those  for  Toluca,  Mexico,  and  Puebla.  The  period 
of  rainfall  represented  by  those  curves  demonstrates 
but  few  interruptions  and  no  delay  whatever  in  the 
rainy  season,  as  it  is  generally  seen  that  the  curve 
begins  to  rise  in  the  months  of  May  or  June. 

In  order  to  discover  what  other  peculiarities  or 
changes  there  may  be,  in  the  latter  as  well  as  in 
other  diagrams,  without  my  referring  to  the  same,  it 
would  be  necessary  to  make  a  more  laborious  and 
detailed  study  than  the  one  afforded  by  the  circum- 
stances and  the  purpose  of  the  present  work. 


RAINFALL         IN         MEXICO 

Toluca,  Mexico 
DATA 

Altitude  above  sea  level  2625  m.  Puga 

Average  annual  pecipitation  678  mm.  " 

Number  of  years  2  " 

Northern  latitude  19°  1 7'  M.  R, 

Average  barometric  pressure,  1896  556  mm  6  " 

Maximum  temperature                "  28°  7'  " 

Minimum            "                        "  3°  8'  " 

Medium               "                        «  13°  8'  " 

Prevailing  direction  of  the  clouds,  1896      N.  E.  " 

winds  «     W.  and  W.  S.  W.  « 

Annual  Precipitation 
and  Number  of  Rainy  Days 

(C.  M.  O.  &  E.  Schulz) 

As  in  some  cases  the  data  I  have  secured  do 
not  agree,  1  have  noted  the  averages : 

1883  729-9-1- 

1884  563.1— 

1892  662.9  average  of  2 — 131— 

1893  843.7  +  160+ 

1894  572.8  —123— 

1895  660.3  average  of  2 — 154+ 

1896  618.8  —146— 

1897  549.6  —123— 

1898  778.5  average  of  2+188+ 

1899  715.1  "        «  24-161  + 

1900  733-7  +146— 

1901  628.2  *— 143 — 
Accepted  average  annual  precipitation       676  mm.  6 
Average  number  of  rainy  days  147^-10  years 
Number  of  years  1 2 

28 


RAINFALL          IN          MEXICO 

The  data  secured  are  insufficient  to  show,  by 
the  mere  inspection  of  the  diagram,  any  change  in 
system  of  rainfall  of  this  locality.  The  line  shows  a 
decrease  in  the  last  years. 

The  course  of  the  line  relating  to  rainy  days  is 
almpst  always  in  accord  with  the  annual  precipitation. 

The  curves  relating  to  monthly  precipitation 
show  a  relative  regularity  during  the  rainy  season. 


RAINFALL          IN          MEXICO 


Mexico,  Federal  District 
DATA 

Altitude  above  sea  level  2282  m.        C.  M.  O. 

Average  annual  precepitation  582  mm.           " 

Number  of  years  20                    " 

Northern  latitude  19°  26'                   M.  R. 

Medium  barometric  pressure  586  mm.  4           " 

Maximum  temperature  31°  6'                      " 

Minimum             "  i°  7' 

Medium              «  15°  4' 

Prevailing  direction  of  the  clouds  S.  W.                      " 

wind  N.  W. 

Number  of  years  15                      " 

Annual  Precipitation  (C.  M.  O.) 

Era  Prior  to  1877 

1841  451-7—  1869       718-3+ 

1842  541.3—       r8;o  695.0+ 

1843  659.6—       1871  746.4+ 

1844  549-0—  1872      758-7+ 

1845  677.0+  1873      596-2— 

1865  1011.0+  1874      737.!  + 

1866  568.1—  1875      669.1— 
1868      692.1  + 

Average  annual   precipitation  for  era 

prior  to  1877  671  mm.  3 

Number  of  years  1 5 

Era  Subsequent  to  1877 

1877  404.0—         1889   408.1— 

1878  892.6+         1890   638.1  + 

1879  477-2—         1891   658.3— 


RAINFALL          IN          MEXICO 

1880  552.2 —  1892  444.2 — 

1 88 1  505.2—  1893  568-6 — 

1882  66i.o-|-  1894  331.8— 

1883  608.7+  1895  559-1— 

1884  468.5—  1896  452.0— 

1885  675.8+  1897  652.1  + 

1886  531.2—  1898  593.7+ 

1887  812.7+  1899  581.1  + 

1888  739-9+         19°°   535-9— 

1901       527.1— 

Accepted  annual  precipitation  for  pre- 
vious era  571  mm.  I 
Number  of  years  25 
Average  annual  precipitation  calculated 

by  all  data  on  hand  608.7 

Number  of  years  40 

The  diagram  for  the  City  of  Mexico,  corre- 
sponding to  last  twenty-five  years,  is  not  of  the  kind 
which  clearly  demonstrates  a  decrease  in  rainfall  by 
simply  glancing  over  the  design. 

The  rising  and  falling  portions  of  the  line  alter- 
nate at  short  intervals. 

The  diagram,  however,  shows,  like  others  I 
have  prepared,  a  period  of  drouth  or  decrease  of 
the  curve  in  the  form  of  a  swing,  in  connection  with 
the  last  part  of  the  period  registered.  It  is  remark- 
able to  see  how  the  line  in  the  last  four  years  shows 
an  uninterrupted  decrease. 

But  the  study  of  the  numerical  data  I  have 
referred  to  above,  is  more  forcible,  to  my  regret, 
than  the  material  inspection  of  the  diagram.  In 
fact,  the  average  for  the  era  prior  to  1877  is  greater 
than  the  total  average,  and  the  former  and  the  latter 


RAINFALL         IN          MEXICO 

are  greater  than  the  average  for  the  era  subsequent 
to  1877,  and>  this  being  one  of  the  localities  where 
the  largest  number  of  data  can  be  obtained,  I  feel 
authorized  to  accept  the  statement  that  rainfall  has 
decreased  at  the  Capitol  of  the  Republic. 

The  curves  relating  to  monthly  precipitation 
cannot  be  considered  very  irregular,  but  I  do  be- 
lieve that  remark  should  be  made  that  during  all 
the  second  part  of  the  period  recorded,  that  is,  dur- 
ing the  last  twelve  or  thirteen  years,  we  have  not 
had  in  the  City  of  Mexico  such  heavy  rainfalls  as 
those  of  the  months  of  July  and  August  of  1878, 
September  1880  and  1886,  and  July  of  1887, 


RAINFALL    IN    MEXICO 

Puebla,  Puebla,  Mexico. 
DATA 

Altitude  above  sea  level  2167  m.  Puga 

Average  annual  precipitation  1185  mm.  " 

Number  of  years  10  " 

Northern  latitude  19°  03'  M.  R. 

Average  barometric  pressure  593  mm.  2       " 

Maximum  temperature  31°  9'  " 

Minimum            "  i°  i'  " 

Medium               "  15°  7'  " 

Prevailing  direction  of  the  clouds          E.   N.  E.  " 

"     "    wind  N.  E. 

Average  annual  precipitation  926.0  " 

Number  of  years  14  " 

Annual  Precipitation 

(  F.  de  P.  Servin  "  State  College",  and  G.  Carrasco  of  the 
"  Catholic  College") 

As  there  are  two  observatories  in  Puebla  fur- 
nishing me  with  data,  I  have  decided  to  prepare  and 
study  two  separate  diagrams  relative  to  the  same 
city,  though  I  did  not  do  likewise  in  regard  to 
Guadalajara,  in  order  to  have  an  idea  of  the  varia- 
tions that  may  occur  through  observations  made 
within  short  distances,  and  I  have  been  really  sur- 
prised at  the  differences  discovered.  I  was  well 
aware  of  the  fact  that  different  precipitation  may  be 
recorded  in  two  separate  wards  of  the  same  city,  but 
when  comparing  the  annual  data  I  did  not  expect 
that  such  marked  differences  would  ever  appear  as 

33 


RAINFALL 


I    N 


MEXICO 


those  shown  by  the  data  mentioned  hereinafter,  or 
as  may  be  seen  from  the  diagrams  I  have  prepared. 
As  I  have  noticed  some  differences  between 
the  data  furnished  me  by  the  C.  M.  O.  relating  to 
the  "  Catholic  College"  at  Puebla,  and  those  pro- 
vided by  the  manager  of  the  latter  observatory,  I 
have  caused  the  averages  to  appear. 

State  College 


1878 

IM7-5+ 

1891 

1025.3+ 

1879 

846.3— 

1892 

824.2— 

1880 

977-7+ 

1893 

1273.8+ 

1881 

912.2+ 

1894 

719.7— 

1882 

930.2+ 

1895 

603.7— 

1883 

974-1  + 

1896 

686.1— 

1884 

673-9— 

1897 

827.9— 

1885 

973-2+ 

1898 

938.8+ 

1886 

750-4— 

1899 

787.0— 

1887 

1193.2+ 

1900 

763-7— 

1888 

984-3+ 

1901 

737-3— 

1889 

790.7— 

1890 

853-5- 

Accepted  average  annual  precipitation 

881  mm 

.8 

Number  of 

years 

24 

Catholic  College 

1877 

925.7  average— 

1891 

1002.4  average  — 

1878 

1281.9        "     + 

1892 

983-9— 

1879 

1016.4        "     — 

1893 

1867.5- 

1880 

1568.5+ 

1894 

757-4— 

1881 

932.0+ 

1895 

644.8— 

1882 

1205.1  average+ 

1896 

688.5— 

1883 

1498.7+ 

1897 

973-0— 

1884 

1105.7— 

1898 

963-0— 

34 


RAINFALL          IN          MEXICO 

1885  1582.24-  1899      900.8  average — 

1886  902.7 —  1900      869.3 — 

1887  1848.5  average-)-        1901       759-7— 

1888  2263.4        "     -f- 

1889  1070.8— 

1890  680.8  average — 

Accepted  average  annual  precipitation     1131  mm.  i 
Number  of  years  25 

The  diagram  prepared  with  the  data  furnished 
by  the  "  Catholic  College"  is  by  far  the  most  irreg- 
ular as  compared  with  the  one  made  with  data  from 
the  "  State  College",  but  the  following  may  be  found 
in  both  of  them :  That  the  curve  falls  twice  in  the 
form  of  a  swing  during  the  second  half  of  the  period 
recorded,  and  that  the  line  of  the  diagram  continues 
to  fall  without  interruption  during  the  last  four  or 
five  years. 

The  curves  relating  to  monthly  precipitation 
are  a  great  deal  more  irregular  in  the  "  Catholic 
College"  than  they  are  in  the  "State  College", 
though  a  general  agreement  is  observed  between 
them. 


35 


RAINFALL          IN          MEXICO 


Pachuca,  Hidalgo,  Mexico 
DATA 

Average  anuaal  precipitation  242  mm.       Puga 

Number  of  years  2 

Altitude  above  sea  level  2460111           M.  R. 

Northern  latitude  20°  07'                  " 

Barometric  pressure  574  mm-  8 

Maximum  temperature  27°  2' 

Minimum          "  0.6' 

Medium            "  13°  7' 

Prevailing  direction  of  the  clouds  S.  W. 

«                 "           «        wind  N.  E. 

Number  of  years  i 

Annual  Precipitation 

(A.  Romero  and  Y.  M.  Cobos) 

1893  475-4—  1898     2952.4+ 

1894  146.5—  1899     2504.3+ 

1895  327.2 —  1900     1060.4 — 

1896  226.5 —  I9°l     2006.0+ 

1897  2749.0+ 

Accepted  average  annual  precipitation  1383.0 

Number  of  years  9 

The  diagram  relating  to  Pachuca  is  the  most 
irregular  of  all  those  I  have  prepared,  and  the  dis- 
crepency  from  one  year  to  the  other,  in  regard  to 
precipitation,  is  so  great  that  one  feels  inclined  to 
doubt  the  veracity  of  the  above  data,  but  fortunately, 
I  sucured  my  information  directly  from  the  manager 
of  the  observatory  at  Pachuca,  who  was  so  kind  as 
to  furnish  the  same,  and,  besides,  the  said  data 
agree  with  those  provided  by  Mexico's  Central 
Meteorological  Observatory. 
36 


RAINFALL         IN         MEXICO 

The  curves  relating  to  monthly  precipitation 
are  equally  irregular  from  one  year  to  the  other,  as 
may  be  understood  from  the  fact  that  the  months  of 
maximum  precipitation  which  were  recorded  in  each 
year  were : 

1893  .  June  177-3 

1894  April  37,1 

1895  October  76.6 

1896  September  £9.7 

1897  July  716.0 

1898  September  737-7 

1899  June  721,2 

1900  December  679.3 

1901  September  870.0 

The  above  is  really  surprising  since  it  is  not 
observed  in  any  other  part  of  the  Republic  from 
where  meteorological  data  can  be  obtained. 

The  above  is  sufficient  in  itself  to  form  an 
opinion  in  regard  to  the  astonishing  irregularity  of 
Pachuca's  system  of  rainfall,  which  could  perhaps 
be  explained  by  being  acquainted  with  the  location 
of  the  city  and  the  orographic  development  of  the 
adjoining  region,  or  through  other  causes  which 
serve  to  establish  the  character  of  the  climate. 

Even  in  other  data  I  have  been  able  to  obtain 
there  is  something  abnormal ;  for  instance,  it  ap- 
pears that  the  prevailing  direction  of  the  clouds  in 
one  year  was  towards  the  southwest,  while  the  pre- 
vailing direction  of  the  wind  in  the  same  year  was 
towards  the  northeast,  that  is,  in  an  entirely  opposite 
direction. 

37 


RAINFALL         IN  MEXICO 

Colima,  Colima,  Mexico 
DATA 

Altitude  above  sea  level  507  m.  Puga 

Medium  annual  precipitation  IO53  mm-  " 

Number  of  years  12  " 

Northern  latitude  19°  n'  M.  R. 

Barometric  pressure                             718  mm.  3  " 

Maximum  temperature  37°  2'  ** 

Minimum           M  9°  4'  « 

Medium             "  24°  8'  «• 

Prevailing  direction  of  the  clouds  S.  W.  •• 

"               "            "      wind  S.  W. 

Number  of  years  i  « 


Annual  Precipitation 

(F.  Castrejon.     Observatory  of  the  Coliraa  Seminary 
and  C.  M.  O.) 

1877  755-4—         1892   892.6— 

1878  1416.5+         1896   749.4— 

1879  1049.9+         1897   898.7— 

1880  960.4—         1898  1038.8+ 
1891  1223.0+         1899  1207.0+ 

1901   859.1 — 

Accepted  average  annual  precipitation     1004  mm.  6 
Number  of  years  x , 

As  there  are  many  years  missing  in  this  series, 
it  is  impossible  to  point  out  any  special  feature  of 
the  diagram. 


RAINFALL         IN          MEXICO 


Mazatlan,  Sinaloa,  Mexico 

DATA 

Altitude  above  sea  level  76  m.  Puga 

Average  annual  precipitation  798  mm,  " 

Number  of  years  20  " 

Northern  latitude  24°  n'  M.  R. 

Average  barometric  pressure              759  mm.  3  " 

Maximum  temperature  34°  i'  " 

Minimum            "  10°  3'  " 

Medium              "  25°  2' 

Prevailing  direction  of  the  clouds  N.  W.  " 

wind  N.  W. 

Average  annual  precipitation  S19-2  " 

Number  of  years  4  ** 


Annual  Precipitation 

and  Number  of  Rainy  Days 

(N.  Gonzales) 

1880  948,6+79  +  1891       390-9—67— 

1881  1454,2+99  +  1892       326.1—60— 

1882  425.6—92  +  1893      777-4—74— 
1-883      748.6—83  -f                    1894       56a2— 62— 

1884  1122.6+102+  1895     1088.5+75  equal 

1885  1117.5+91  +  1896       594.2 — 70 — 
*886      799-5—74  —  l897      695.3—67— 

1887  1206.4+91  +  1898      663.5    63— 

1888  676.1—76  +  1899      852,1+54— 
1*89      834,4+77  +  1900      812.6+59^- 
1890      685.8—73  —                   1901      948.5+71— 

Accepted  average  annual  precipitattion      ^05  mm.  8 
Average  number  of  rainy  days  7j 

39 


RAINFALL          IN          MEXICO 

The  diagram  showing  Mazatlan's  annual  rain- 
fall offers  many  irregularities,  and  the  same  demon- 
strates a  decrease,  followed  by  a  rise  in  the  curve, 
such  as  has  been  noticed  in  other  cities,  commenc- 
ing in  the  present  case  in  1887  and  reaching  its 
maximum  elevation  in  1895,  dropping  once  more 
during  the  following  year  and  again  rising  with 
slight  alternate  interruptions  during  the  last  five 
years. 

The  curves  relating  to  monthly  precipitation 
show  greater  irregularities  than  those  for  other 
cities  of  the  Republic,  such  as  Mexico,  Toluca,  and 
Puebla,  and  the  same  are  more  remarkable  because 
there  are  slight  interruptions  during  the  rainy 
season ;  that  is  to  say,  that  the  curve  rises  and  falls 
uniformly  without  projecting  in  or  out.  The  great- 
est irregularities  consist  in  the  discrepancies  found 
between  the  months  of  heaviest  rains  in  one  year 
and  those  of  the  other,  therefore,  the  curve  ap- 
pears quite  high  in  some  years  and  very  low  in 
others. 

In  regard  to  the  diagram  referring  to  rainy 
days  of  each  year,  it  is  worthy  of  note  that  prior  to 
1889  there  is  not  a  single  year  showing  a  marked 
decrease  below  the  normal  line,  as  only  the  year 
1886  has  one  rainy  day  less,  while  after  1899  a11  the 
years  are  inferior,  with  the  exception  of  1895,  which 
was  equal  to  the  normal  average. 

The  appearance  of  the  diagram  shows,  in  a 
general  way,  that  rainfall  has  decreased. 


RAINFALL         IN         MEXICO 


Monterrey,  Nuevo  Leon,  Mexico 
DATA 

Altitude  above  sea  level  496  m.  Puga 

Northern  latitude       ,  25°  40'  M.  R, 

Average  barometric  pressure  709  mm.  I  " 

Maximum  temperature  33°  2'  " 

Minimum            "  li°  7'  " 

Medium              "  21°  o'  " 

Prevailing  direction  of  the  wind  S.  E.  " 

Number  of  years  I  *' 


Annual  Precipitation 

(A.  Carrillo) 

1865  744-0—  1893  I37.0— 

1885  427.0—  1894  489-9+ 

1886  417-5—  1895  549-9+ 

1887  449-0—  1896  628.0+ 

1888  341.3—  1897  581.0+ 

1889  283.2—  1898  488.8+ 

1890  338-6—  1899  969-4+ 

1891  264.2 —  1900  795-6+ 

1892  1 86.6 —  1901  729.7+ 

Accepted  average  annual  precipitation       475  mm.  I 
Number  of  years  17 

The  diagram  showing  Monterey's  annual  rain- 
fall is  remarkable  because  of  its  rises  and  falls, 
which  follow  a  continuous  course  during  long 
periods  of  time.  No  sudden  changes  are  to  be 
noticed,  such  as  happen  with  diagrams  of  other 


RAINFALL         IN         MEXICO 

observatories.  Another  feature  worthy  of  mention 
in  this  diagram  is  that  it  follows  a  course  which 
differs  from  the  others  generally,  at  least  in  regard 
to  years  where  pluviometric  registers  have  been 
secured.  Prior  to  1883  a^  tne  years  had  a  precip- 
itation below  the  normal  figures,  but  the  reverse 
happened  after  the  above  mentioned  date. 

As  may  be  seen  the  diagram  demonstrates  an 
increase  in  rainfall. 

It  is  to  be  regretted  that  only  seventeen  years 
of  observation  can  be  secured  from  this  observatory, 
since  the  latter  is  so  important,  owing  to  its  location 
and  on  account  of  the  features  shown  by  the  dia- 
gram prepared  for  years  recorded. 

The  curves  relating  to  monthly  precipitation 
are  interesting  because  of  the  irregularities  they 
indicate,  owing  to  a  period  of  relative  drouth  which 
always  interrupts  the  rainy  season. 

Mention  is  equally  made  of  the  low  precipita- 
tion had  during  the  months  of  heavy  rains  corre- 
sponding to  the  first  part  of  the  period  registered. 

The  year  1888  is  worthy  of  note,  because  what 
little  rain  it  had  was  distributed  over  almost  all  the 
months  of  the  year,  November  having  been  the 
month  of  heaviest  rains,  with  a  very  limited  precip- 
itation of  27  mm.  3. 


RAINFALL         IN         MEXICO 


Merida,  Yucatan,  Mexico 

DATA 

Altitude  above  sea  level  9  m.  Puga 

Average  annual  precipitation  830  mm.  " 

Number  of  years  2  " 

Northern  latitude  20°  55'  M.  R. 

Average  barometric  pressure               760  mm.  5  " 

Maximum  temperature  40°  5'  " 

Minimum            "  12°  i'  " 

Medium              "  25°  8'  " 

Prevailing  direction  of  the  clouds  E.  " 

wind  N.  E.  " 

Number  of  years  I  (1896) 


Annual  Precipitation 
and  Number  of  Rainy  Days 

(Estatistical  Bulletin  from  Yucatan) 


1875 

913.0  — 

1896 

914.7+118+ 

1890 

864.0— 

1897 

875-0+ 

1891 

911.0+ 

1898 

1139.9+124+ 

1892 

834.0— 

1899 

1062.5+  78— 

1893 

560.0  — 

1900 

943-6+  93— 

1894 

957-2+  94— 

1901 

601.7  —  65  —  • 

1895 

744.0—  97+ 

Accepted  average  annual  precipitation       867  mm.  3 
Average  number  of  raing  days  in  7  years  95 

Number  of  years  12 


RAINFALL         IN         MEXICO 

Though  there  are  but  few  years  recorded,  the 
diagram  shows  an  annual  increase  of  rainfall  similar 
to  the  one  registered  in  other  observatories  during 
the  last  four  to  eight  years,  preceded  by  a  period  of 
years  generally  poor  representing  in  the  curve  the 
descending  portion  already  mentioned  in  this  study. 

The  examination  of  the  diagram  will  not  demon- 
strate either  an  increase  or  a  decrease  in  rainfall. 

As  regards  monthly  precipitation,  and  the  num- 
ber of  rainy  days  of  each  year,  for  which  I  have  pre- 
pared curves  corresponding  to  the  last  seven  years, 
there  is  but  little  to  be  said. 


RAINFALL         IN          MEXICO 

Tuxpam,  Veracruz,  Mexico 
DATA 

Average  annual  precipitation                           1532  mm.  Puga 

Number  of  years                                                     5  " 

Northern  latitude                                          20°  59'  M.  R. 

Average  barometric  pressure                    763  mm.  " 

Average  temperature                                      24°  5'  " 

Prevailing  direction  of  the  clouds                N.  W.  " 

"                "            "       wind                        W.  " 

Average  annual  precipitation              1654  mm.  3  " 

Number  of  years                                                    2  " 


Annual  Precipitation  (C.  M.  O.) 

1879  1 592-5+  l885  893-° — 

1881  1505.5+  1889  1716.1+ 

1883  1589.0+  1890  1199.1 — 

1884  1109.3 —  l89x  J  839.0+ 

Accepted  average  annual  precipitation  1430.4 

Number  of  years  8 

The  only  thing  worthy  of  mention  at  Tuxpam 
is  that  it  holds  the  third  place  among  the  list  of 
towns  in  Mexico  provided  with  a  meteorological 
observatory,  on  account  of  its  average  annual  pre- 
cipitation. 


45 


RAINFALL         IN         MEXICO 


Teziutlan,  Puebla,  Mexico 

DATA 

Altitude  above  sea  level  1982  meters    Puga 

Average  annual  precipitation  1531  mm.  " 

Number  of  years  5  " 


Annual  Precipitation  (C.  M.  O.) 

1878  1339.2—  1882    1263.2— 

1879  1927.2+  1884    1240.6— 
1881     1884.2+                    1888    2268.2+ 

Accepted  average  annual  precipitation  1653.7 

Number  of  years  6 

Considering  Teziutlan 's  average  annual  precip- 
itation, it  holds  the  first  place  among  towns  from 
which  we  have  data  covering  six  or  more  years. 


RAINFALL          IN          MEXICO 


Real  del  Monte,  Hidalgo,  Mexico 
DATA 

Annual  Precipitation  (C.  M.  O.) 

1889  768.2+  1895      621.1— 

1890  828.04-  1896      435.0 — 

1891  1023.0+  1897      779-9+ 

1892  853.0+                     1898  9*7-9+ 

1893  156.0 —                     1899  689.0 — 

1894  565-7—                     1900  955-0+ 
Accepted  average  annual  precipitation  749  mm.  2 
Number  of  years  12 

The  rise  and  fall  of  the  curve  is  well  defined  in 
the  diagram  for  Real  del  Monte,  said  curve  com- 
mencing in  1891  and  ending  in  1898,  and  of  which 
fact  I  have  made  several  mentions  in  the  course  of 
this  study,  in  reference  to  other  observatories. 


47 


RAINFALL          IN  MEXICO 

Tacubaya,  D.  F. 
DATA 

Altitude  above  sea  level  2323  m.  Puga 

Average  annual  precipitation  683  mm.  " 

Number  of  years  10  " 

Northern  latitude  19°  12'  M.  R. 

Average  barometric  pressure  583  mm.  6  " 

Maximum  temperature  28°  6'  " 

Minimum          "  o°  8'  " 

Medium             "  15°  5'  " 

Prevailing  direction  of  the  wind  N.  W.  " 

Average  annual  precipitation  668  mm.  i 

Number  of  years  9 


Annual  Precipitation 

(  M.  Moreno  y  Anda ) 

1884  492.6—         1892  485.7— 

1885  679.6+         1893  726.8+ 

1886  582.9 —         1894  388.5— 

1887  846.5+         1895  627.8— 

1888  632.2—         1896  440.3— 

1889  713-2+         1897  665.4+ 

1890  792.5+         1898  681.1  + 

1891  883.0+         1899  626.8— 

1900  668.8+ 

Accepted  average  annual  precipitation       643  mm.  i 
Number  of  years  17 

The  diagram  relative  to  rainfall  at  Tacubaya 
demonstrates  a  decrease  at  first  sight  during  the 
period  registered,  and  as  it  is  natural  to  suppose, 

48 


RAINFALL          IN          MEXICO 

it  is  quite  similar  to  that  of  the  City  of  Mexico, 
owing  to  the  proximity  of  both  observatories.  We 
fail  to  discover  between  the  two  diagrams  mentioned 
such  marked  differences  as  shown  between  diagrams 
prepared  with  the  data  secured  from  the  "  Catholic  " 
and  the  "  State  Colleges  "  at  Puebla. 


49 


RAINFALL 


I    N 


MEXICO 


Pabellon,  Aguascalientes,  Mexico 


DATA 

Altitude  above  sea  level 

Average  annual  precipitation 

Number  of  years 

Northern  latitude 

Average  barometric  pressure 

Maximum  temperature 

Minimum          " 

Medium 

Prevailing  direction  of  the  clouds 

"  "  "      wind 

Average  annual  precipitation 
Number  of  years 


S. 


1924  m.  Puga 

506  mm.          " 

19 
22°  04'  M.  R 

607  mm.  8       " 
24°  o' 

12°  2'  " 

18°  2' 
S.  E. 


W.   S.  W. 

537  mm.  o 
10 


Annual  Precipitation  (C.  M.  O.) 


1877  337-4 — 

1878  467.1— 

1879  434-4— 

1880  697.4+ 

1881  602.  i  + 

1882  444.2 — 

1883  605.5+ 


1884  262.1— 

1885  648.5+ 

1886  539.2+ 

1887  669.1  + 

1888  758.9+ 

1889  566.6+ 

1890  344-0— 


Accepted  average  annual  precipitation  529-7 

Number  of  years  14 


The  above  diagram  shows  an  increase  of  rain- 
fall during  the  period  recorded,  although  on  a  very 
limited  scale. 


RAINFALL          IN          MEXICO 


Huejutla,  Hidalgo,  Mexico 
DATA 

Altitude  above  sea  level  376  m.          Puga 

Average  annual  precipitation  466  mm.  ( ? )  " 

Number  of  years  4 

Northern  latitude  21°  41'             M.  R. 

Average  barometric  pressure  765  mm.  I       " 

Maximum  temperature  34°  o'                  " 

Minimum          "  10°  o'                 " 

Medium            «  23°  o' 

Number  of  years  i 


Annual  Precipitation  (C.  M.  O.) 

1882  1154.6—       1886  1165.2— 

1883  1215.0 —       1889  2109.3+ 

1884       1247.2—  1890       II2I.8— 

1885    1093.7—  1891    1383.3+ 

Accepted  average  annual  precipitation     1311  mm.  2 
Number  of  years  8 


RAINFALL          IN          MEXICO 

San  Luis  Potosi,  San  Luis  Potosi, 
Mexico 

DATA 

Altitude  above  sea  level  1890  m.  Puga 

Average  annual  precipitation  398  mm.           " 

Number  of  years  10                  " 

Northern  latitude  22°  09'  M.  R 

Average  barometric  pressure  613.4                   " 

Maximum  temperature  33°  9'                  " 

Minimum           "  i°  8'                  " 

Medium             "  17°  4' 

Prevailing  direction  of  the  clouds  W.                  " 

"                 "           "        wind  E.                   " 

Average  annual  precipitation  389  mm.  o 

Number  of  years  9 

Annual  Precipitation 

( San  Luis  Institute  and  C.  M.  O.) 


1878 

432-4+ 

I890 

531-2  + 

1879 

380.2  av.  2+ 

I89I 

257.6  av.  2  — 

1880 

359-2+ 

1892 

244.5  "   2— 

1881 

444-0+ 

1893 

4I4.I   "  2  + 

1882 

347-5— 

I894 

229.1  — 

1883 

404.0+ 

1895 

285.7- 

1884 

189.9— 

I896 

249.7  av.  2 

1885 

484.0+ 

I897 

367.8+ 

1886 

403-3+ 

1898 

383.5+ 

1887 

506.8+ 

1899 

2OO.I  — 

1888 

504.8  av.  2+ 

I9OO 

264.0  — 

1889 

331.0"   2— 

Accepted  average  annual  precipitation       357.1  mm. 

Number  of  years  23 

52 


RAINFALL          IN          MEXICO 

The  diagram  relating  to  rainfall  at  San  Luis 
could  not  be  classified  as  one  of  the  most  irregular, 
since  it  does  not,  like  in  many  other  cities  of  small 
precipitation,  depart  very  much  from  the  average 
line  of  rainfall. 

The  examination  of  the  diagram  will  show  a 
decrease  of  rainfall  during  the  latter  part  of  the 
period  recorded,  as  subsequent  to  1890  all  years 
appear  below  the  normal  line  with  the  exception  of 
three  of  them,  1893,  1897,  and  1898. 


RAINFALL 


I    N 


MEXICO 


Tepic,  Tepic,  Mexico 
DATA 

Altitude  above  sea  level  1051  m.       C.  M.  O.     Puga 

Average  annual  precipitation          1090  mm. 
Number  of  years  7 

Annual  Precipitation  (C.  M.  O.) 

Era  Prior  to  1877 


1844  1270.0 — 

1845  1066.8 — 

1846  1524.0+ 

1847  1765-3+ 

1848  1727-7+ 
J849  I955-8+ 

1850  1892.3+ 

1851  1638.3+ 

1852  1447-8+ 
'853  1333-5+ 


1854 
1855 
1856 
1857 
1858 

1859 
1866 
1867 
1868 


Average  annual  precipitation  for  era 

prior  to  1877 
Number  of  years 


1651.0+ 
1231.9— 

774-7— 
609.6 — 

952.5— 
1854.2+ 
1498.6+ 

1384-3- 
1663.7+ 


1433.7  mm. 
19 


Era  Subsequent  to  1877 

1885  I447-8+         1890  1409.7+ 

1886  1155.7—         1891  1371.6— 

1887  1473-2+         1892  1231.6— 

1888  1676.4+         1893  1600.2+ 

1889  1244.6—         1894  1181.1— 


Accepted  average  annual  precipitation, 

era  subsequent  to  1877 
Number  of  years 
Average  annual   precipitation,  figured 

out  with  all  data  at  hand 
Number  of  years 


1379.1  mm. 
10 

1414.8  mm. 
29 


RAINFALL          IN 


- 


ITY 


M    E    X 


Oaxaca,  Oaxaca,  Mexico 

DATA 

Altitude  above  sea  level  1546  m. 

Average  annual  precipitation  715  mm. 

Number  of  years  3 

Northern  latitude  17°  04' 

Average  barometric  pressure  636.6  mm. 

Maximum  temperature  32°  9' 

Minimum           "  6°  2' 

Medium             "  20°  6' 

Prevailing  direction  of  the  wind  W. 

Annual  Precipitation  (C.  M.  O.) 


1878 

578.0— 

1879 

95l-°+ 

1880 

617.1  — 

1883 

858.9+ 

1884 

S^-S— 

1885 

550-6— 

1886 

940.9+ 

1887 

1080.7+ 

1888 

1161.0+ 

1889 

729-3— 

1890 
i89i 
1892 

1893 
1894 

1895 
1896 
1897 


714.4— 

1032.4+ 
849-2+ 

1098.1  + 
663.7- 

7I3-3— 
700.2 — 

843-9+ 
880.5+ 


Puga 


M.  R. 


Accepted  average  annual  precipitation       814.7  mm. 
Number  of  years  19 

The  diagram  relating  to  rainfall  in  Oaxaca 
shows  a  fall  in  the  curve  subsequent  to  1893,  the 
same  as  is  noticed  in  the  diagrams  for  other  places 
I  have  prepared,  but  in  a  general  way  it  does  not 
indicate  a  decrease  in  rainfall,  because  prior  to  1886 
there  are  similar  and  even  greater  decreases  in  this 
place,  the  four  years  of  minimum  precipitation  re- 
corded appearing  prior  to  the  above  mentioned  date. 

55 


RAINFALL         IN          MEXICO 


Morelia,  Michoacan,  Mexico 

DATA 

Altitude  above  sea  level  1940  m.     Moreno 

Average  annual  precipitation  728  mm.  " 

Number  of  years  2  " 

Northern  latitude  19°  42'  M.  R. 

Average  barometric  pressure  608.8  mm.  " 

Maximum  temperature  31°  5'  " 

Minimum          "  i°  5'  " 

Medium            "  16°  8' 

Prevailing  direction  of  the  clouds  W.  " 

"                "           "       wind             S.   S.  W.  " 

Year  1896 


Annual  Precipitation  (C.  M.  O.) 

1882  648.8 —       1898  707.9+ 

1894  527.64-       1899  772.6+ 

1895  837.2+       1900  626.7 — 

1896  619.9—       1901  831.1  + 

1897  580.3— 

Accepted  average  annual  precipitation  683.5 

Number  of  years  9 


5'' 


RAINFALL         IN         MEXICO 


Jalapa,  Veracruz,  Mexico 
DATA 

Altitude  above  sea  level  1321  m.      Moreno 

Average  annual  precipitation  J54O  mm.        " 

Number  of  years  2 

Northern  latitude  19°  31'              M.  R, 

Average  barometric  pressure  649.3  mm>         " 

Maximum  temperature  33°  5'                 " 

Minimum           "  5°  6'                 " 

Medium             "  18°  5' 

Prevailing  direction  of  the  wind  N.                   " 

Year  1896                  " 


Annual  Precipitation  (C.  M.  O.) 

1894  917.5 —       1898  2156.1+ 

1895  1306.0 —       1899  1670.7+ 

1896  1779.4+        1900  1611.1  + 

1897  1193-3— 

Accepted  average  annual  precipitation  1519.2 

Number  of  years  7 

By  examining  Jalapa's  diagram  an  increase  of 
rainfall  will  be  discovered,  but  this  indication  is  of 
a  very  limited  value  owing  to  the  fact  that  only  a 
few  years  have  been  registered. 


57 


RAINFALL   IN   MEXICO 


Guanajuato,  Guanajuato,  Mexico 

DATA 

Altitude  above  sea  level  2060  m.  Puga 

Average  annual  precipitation  859  mm.  " 

Number  of  years  6  " 

Northern  latitude  21°  01'  M.  R. 

Average  barometric  pressure  601.3  mm.  " 

Maximum  temperature  30°  7'  " 

Minimum           "  i°  3'  " 

Medium             "  17°  6'  " 

Average  annual  precipitation  964.5  mm  .     " 

Number  of  years  5  " 


Annual  Precipitation  (C.  M.  O.) 


1881  893.5+  J892  452.0  — 

1883  945-2+  1893  532-5^ 

1884  503-8  —  1894  546.0  — 

1885  1070.7+  1895  578-2  — 

1886  756.1+  1896  524.2— 

1887  987.7+  1897  639.5— 

1888  789.2+  1898  798.4+ 

1889  640.5—  1899  631.3+ 

1890  601.1  —  1900  651.1  + 

1891  590.2  — 

Accepted  average  annual  precipitation  691.1 

Number  of  years  19 

I  believe  that  none  of  the  diagrams  I  have  pre- 

pared is  more  interesting  than  that  of  Guanajuato, 

the  same  being  the  one  that  shows  the  curve  in  the 

form  ofa    swing  and  spread  out  wider,  as  it  begins 

58 


RAINFALL          IN          MEXICO 

to  fall  in  1887  and  rises  about  1900 ;  that  is  to  say, 
it  covers  a  period  of  fourteen  years,  an  incident 
which  does  not  occur  in  any  of  the  other  diagrams. 
Such  a  long  lapse  of  time  in  which  the  amount  of 
rainfall  begins  first  by  decreasing  and  then  by 
rising  without  interruption,  is  not  shown  by  any  of 
the  other  diagrams  I  have  prepared. 


RAINFALL         IN         MEXICO 


Aguascalientes,  Aguascalientes, 

Mexico 

DATA 

Altitude  above  sea  level  1861  m.  Puga 

Average  annual  precipitation  591  mm.  " 

Number  of  years  6  " 

Northern  latitude  21°  53'  " 

Average  barometric  pressure  605.1  mm.  " 

Maximum  temperature  29°  5'  " 

Minimum           "  2°  8'  " 

Medium            "  18°  6'  " 


Annual  Precipitation  (C.  M.  O.) 

1879     418.4—                  1885  762.4+ 

1882  675.0+                  1886  594.5+ 

1883  529.6—                  1889  542.2— 

1884  474-3— 

Accepted  average  annual  precipitation  57°-9 

Number  of  years  7 


RAINFALL          IN          MEXICO 

Linares,  Nuevo  Leon,  Mexico 
DATA 

Altitude  above  sea  level  362  m. 

Minimum  temperature  in  six  years  9°  in 

February,  n  to  14,  1899 

Medium  temperature  in  six  years  22°  4' 

Number  of  years  6 


Annual  Precipitation 
and  Number  of  Rainy  Days 

( Martin  Stecker ) 

1896  796—56                        ^99  789—49 

1897  8874-60                       1900  990-|-66 

1898  543— 51                       !901  1014+53 
Accepted  annual  precipitation  836  mm. 
Number  of  years  used  in  calculation  6 

The  examination  of  the  above  diagram  does  not 
permit  us  to  appreciate  whether  there  has  been  any 
increase  or  decrease  of  annual  rainfall  at  Linares, 
because  of  the  limited  number  of  years  observed. 

Three  of  the  years  recorded  appear  over  and 
three  under  the  normal  line. 

In  the  curves  relating  to  monthly  precipitation, 
which  I  have  also  prepared  with  the  data  kindly  fur- 
nished me  by  Mr.  Stecker,  it  appears  that  the  pre- 
cipitation is  heavier  during  two  portions  of  the  year, 
which  fact  does  not  happen  in  other  localities. 


RAINFALL          IN          MEXICO 

The  curves  comprise  two  ascending  parts, 
pretty  well  marked  in  the  years  1896,  1897,  1899, 
and  1901.  There  are  one  or  several  months  of 
heavy  precipitation  missing  for  1898  in  order  to 
determine  the  first  rise  of  the  curve,  and  during 
1900  the  second  rise  was  not  so  well  characterized. 


RAINFALL          IN          MEXICO 

Zapotlan,  Jalisco,  Mexico 
DATA 

Altitude  above  sea  level  1530  m.        Moreno-Puga 

Northern  latitude  19°  36'              M.  R. 

Average  barometric  pressure  636.8  mm.          " 

Maximum  temperature  36°  9'                  " 

Minimum           "  6°  o'                 " 

Medium             «  20°  5' 

Prevailing  direction  of  the  clouds  N.  E.                  " 

wind  S.  E. 

Number  of  years  i  (1896)       " 


Annual  Precipitation  (C.  M.  O.) 

( S.  Diaz) 

1894  663.0—                       1898  1027.7  + 

1895  836.3—                       1899  963-5+ 

1896  915.9+                     1900  ioo8.i-f 

1897  886.5 —                     1901  iooi.8-f 
Accepted  average  annual  precipitation  912.8 
Number  of  years  used  in  calculation  8 

The  examination  of  the  diagram  shows  an 
increase  in  rainfall  during  the  years  recorded  and 
the  slight  decreases  that  appear  therein,  the  curve 
never  falls  to  the  point  equal  to  that  of  the  precip- 
itation of  the  previous  year  in  each  case. 

In  the  first  period  of  four  years  there  is  only 
one  year,  1896,  that  exceeds  the  normal  line  a  little, 
the  other  three  being  below  the  latter.  In  the 
second  period  of  four  years  the  whole  four  had  a 
precipitation  higher  than  the  accepted  average. 
63 


RAINFALL          IN          MEXICO 

The  curves  relating  to  monthly  precipitation, 
during  the  years  recorded,  show  a  regular  condition 
during  the  rainy  season,  rainfall  being  fairly  well 
distributed,  as  starting  in  April  and  continuing 
through  May  and  June,  the  curve  keeps  on  rising 
and  it  does  not  drop  down  until  November  or 
December  of  each  year. 


RAINFALL 


I  N 


MEXICO 


Queretaro,  Queretaro,  Mexico 


DATA 


Altitude  above  sea  level 

Annual  precipitation 

Number  of  years 

Northern  latitude 

Average  barometric  pressure 

Maximum  temperature 

Minimum  " 

Medium  " 

Prevailing  direction  of  the  wind 

Number  of  years 


1850  m. 
569  mm. 

17 

20°  35' 
613.8  mm. 

33°  i' 

18°  i' 

E. 

3 


Puga 


M.  R. 


Annual  Precipitation  (C.  M.  O.) 


1877  577.I  + 

1878  675.1  + 

1879  562.9+ 

1880  638.5+ 

1881  665.6+ 

1882  480.0— 

1883  577.8+ 

1884  295.4 — 

1885  631.8+ 

1886  606.7+ 

1887  500.0+ 

1888  480.0— 

1889  440.9— 


1890  539.9+ 

1891  471-1— 

1892  374-7— 

1893  641.1  + 

1894  372.2— 

1895  252.7— 

1896  290.0 — 

1897  518.6+ 

1898  509.1  + 

1899  563-7+ 

1900  338.2 — 

1901  214.4 — 


Accepted  average  annual  precipitation       489.1  mm. 
Number  of  years  used  in  calculation  25 


RAINFALL         IN          MEXICO 

The  examination  of  the  diagram  corresponding 
to  Queretaro  clearly  indicates  that  there  has  been  a 
decrease  in  rainfall  in  that  city,  and  it  shows  the 
period  of  drouth  appearing  in  other  diagrams  pre- 
pared by  me,  with  a  considerable  fall  of  the  curve, 
in  the  shape  of  a  swing,  corresponding  to  the  last 
period  of  five  years. 

The  only  complete  data  relating  to  monthly  pre- 
cipitation that  I  have  been  able  to  secure  are  those 
from  1893  up  to  date,  and  from  the  examination  of 
the  proper  curves  I  have  drawn,  it  can  be  seen  that 
there  is  no  uniformity  between  the  curves  covering 
several  years. 


66 


RAINFALL    IN    MEXIC  O 

Hacienda  del  Carmen, 

Guemez,  Tamaulipas,  Mexico 

Annual  Precipitation 

(  Francisco  Benitez  Leal,  C.  E.) 

1897  866-f  1900      373— 

1898  827+  1901      823+ 

1899  535— 

Accepted  average  annual  precipitation       684.8  mm. 
Number  of  years  5 

Although  there  are  only  five  years  of  observa- 
tion at  the  latter  place,  the  proper  data  having  been 
furnished  to  me  through  the  kindness  of  Mr.  Benitez 
Leal,  I  have  endeavored  to  prepare  the  correspond- 
ing diagram,  and  I  will  take  into  account,  in  the 
general  study  I  am  preparing,  the  course  of  precip- 
itation at  Guemez,  feeling  really  thankful  that  I  was 
able  to  secure  the  necessary  data,  as  it  is  the  only 
point  within  the  State  of  Tamaulipas  wherefrom  I 
succeeded  in  getting  the  desired  information. 

The  diagram  shows  a  decrease  from  the  first 
year  recorded  until  we  get  to  the  one  next  to  the 
last,  but  an  increase  in  the  precipitation  takes  place 
immediately  after  such  period,  which  places  the  line 
in  the  extreme  almost  as  high  as  the  starting  point. 

The  curves  relating  to  monthly  precipitation  are 
very  irregular,  and  there  is  not  a  single  special  fea- 
ture about  them  that  would  make  them  worthy  of 
notice. 

67 


RAINFALL          IN          MEXICO 

I  have  made  use  of  the  data  I  was  able  to 
obtain,  believing  that  they  comprise  the  greater  part 
of  information  that  could  be  utilized  in  a  study  of 
this  nature.  I  have  prepared  the  diagrams  of 
annual  precipitation  for  each  of  the  localities  where 
there  are  meteorological  observatories,  and  the 
curves  relating  to  monthly  rainfall  for  such  points 
as  I  have  succeeded  in  securing  the  necessary  data, 
and  I  have  made  notations  pointing  out  the  peculiar- 
ities I  have  considered  worthy  of  mention  when  pre- 
paring the  former  as  well  as  the  latter. 

I  will  now  proceed  to  make  a  recapitulation  of 
the  latter  data  to  the  end  of  discovering  whether 
they  will  serve  to  decide  the  following  questions  : 

first.  What  has  been  the  change  in  the  rain- 
fall system  of  the  country  ? 

Second.  The  change  that  may  have  occurred, 
has  it  been  permanent  during  the  last  quarter  of  the 
nineteenth  century,  or  has  it  been  more  marked  at 
certain  epochs  ? 

Third.  Has  the  change  been  general  all  over 
the  country,  and  what  may  have  been  the  cause  of 
such  change  ? 

Fourth.     What  may  we  expect  in  the  future  ? 

Fifth.     What  can  we  do  to  remedy  the  evil  ? 

See  Enclosure  No.  2.  (A  synoptical  chart  of 
pluviometric  observations  ). 


RAINFALL          IN          MEXICO 

Study  of  the  Chart 

In  the  first  column  appear  the  names  of  the 
localities  from  where  I  have  been  able  to  secure  plu- 
viometric  reports. 

In  the  second  column  appear  the  periods  of 
years  for  which  I  have  pluviometric  reports  and  the 
names  of  the  persons  who  were  so  kind  as  to  furnish 
me  with  them,  the  majority  of  said  persons  being  the 
managers  of  the  respective  observatories.  The  ab- 
breviation, C.  M.  O.,  means  that  the  data  have  been 
secured  from  the  Central  Meteorological  Observa- 
tory of  Mexico,  which  institution  published  some 
time  ago  a  pamphlet  containing  some  of  the  data  in 
question,  the  same  having  been  corrected  at 'a  later 
date. 

Column  three  shows  the  averages  I  have  ac- 
cepted, calculated  from  the  greatest  possible  number 
of  years,  subsequent  to  1877,  relating  to  amount  of 
annual  rainfall  had  at  the  corresponding  localities. 

These  figures  indicate  in  the  diagram  of  precip- 
itation the  value  of  the  horizontal  line  to  which  I 
have  subjected  the  elevations  of  annual  rainfall. 

Column  four  denotes  the  number  of  years  upon 
which  the  above  averages  were  calculated,  to  the  end 
that  the  correctness  of  each  may  be  appreciated. 

Columns  five  and  six  denote,  respectively,  the 
maximums  and   minimums  of   annual  precipitation 
during  the  whole  period  recorded,   and  the   years 
corresponding  to  each  column. 
69 


RAINFALL          IN          MEXICO 

Column  seven  indicates  the  separation  between 
the  maximum  and  minimum  annual  precipitation. 
The  latter  difference  is  remarkable  in  regard  to  sev- 
eral observatories,  and  the  same  clearly  demonstrates 
the  irregularities  of  our  rainfall,  but  I  do  not  believe 
that  this  is  an  exceptional  feature  of  our  climate,  as 
some  people  contend,  as  similar  and  even  greater 
differences  are  recorded  in  other  countries. 

My  intention,  in  preparing  columns  five  and 
six,  was  to  study  whether  any  relation  could  exis- 
between  the  succession  of  years  of  maximum  and 
minimum  precipitation,  with  the  increase  and  de- 
crease of  the  average  amount  of  rain  falling  annu- 
ally at  each  place  ;  but  I  have  failed  to  discover  any 
relation  whatever,  since  in  sixteen  cases  the  year  of 
heavier  rainfall  comes  before  the  year  of  less  precip" 
itation,  and  in  seventeen  cases  the  matter  appears 
to  be  the  other  way.  The  difference,  therefore, 
would  not  justify  any  deduction. 

In  order  to  investigate  whether  there  is  any  ten- 
dency in  our  rainfall  to  decrease  or  increase,  if  we 
had  in  all  our  observatories  the  pluviometric  records 
for  the  same  period  of  time,  all  we  would  have  to  do 
would  be  to  divide  such  periods  in  two  epochs,  and 
compare  the  average  precipitations  calculated  for 
each  epoch ;  but  we  are  not  in  condition  to  do  that, 
because  only  a  few  observatories  have  any  registers 
prior  to  1877  ;  there  are  some  which  were  in  opera- 
tion during  a  certain  period  of  years  but  do  not  exist 
at  present ;  others  were  established  lately  and  con- 


RAINFALL         IN         MEXICO 

tinue  to  make  pluviometric  observations,  and  there 
are  many  which  did  work  continually. 

As  it  has  been  my  desire  to  base  my  conclu- 
sions upon  the  greatest  possible  number  of  years 
recorded,  and  have  tried  to  avail  myself  of  all  of  the 
few  elements  to  be  depended  upon,  what  I  have 
done  is,  to  divide  the  era  that  has  been  recorded  in 
each  case  in  two  periods,  first  and  second,  for  which 
I  have  calculated  separately  the  proper  average  pre- 
cipitation, entering  the  same  in  columns  eight  and 
nine. 

When  the  total  number  of  years  recorded  is  an 
odd  number,  I  have  not  taken  into  consideration  the 
precipitation  of  the  middle  year  of  the  series,  to  the 
end  of  avoiding  comparison  between  averages  calcu- 
lated with  a  different  number  of  years,  although  I 
am  convinced  that  the  results  would  not  have  been 
altered  in  none  of  the  sixteen  cases  of  an  odd  series 
of  years. 

In  column  ten  I  denote  by  means  of  the  marks 
of  plus  and  minus  whether  there  has  been  any 
increase  or  decrease  in  the  average  precipitation  of 
each  period,  and  the  result  thus  obtained  is,  to  my 
regret,  quite  eloquent,  there  being  twenty-one  minus 
signs  against  twelve  plus  marks. 

We  could  argue  against  the  foundation  of  the 
above  conclusion  that  the  first  and  second  periods, 
in  the  different  cases,  do  not  refer  to  the  same  era, 
that  is  to  say,  that  the  same  years  are  not  contained 
in  all  of  the  latter,  because,  speaking  about  the  City 


RAINFALL         IN          MEXICO 

of  Mexico,  for  instance,  the  first  period  runs  from 
1877  to  1888,  while  when  referring  to  Linares  it 
runs  from  1886  to  1898  ;  but  I  believe  such  argu- 
ment could  be  destroyed  by  the  sole  idea  that  the 
object  of  the  comparison,  condensed  in  column  ten, 
is  to  find  out  only  whether  there  has  been  any  gen- 
eral tendency  towards  a  decrease  or  increase  of 
rainfall. 

The  results  of  such  comparison,  for  the  era  I 
have  studied,  would  attain  the  greatest  possible 
value  if  all  the  observatories  could  furnish  pluviom- 
etric  reports  from  1877  to  1901,  but,  unfortunately, 
this  is  not  so.  After  this  consideration,  the  results 
of  such  comparison  would  be  of  the  greatest  possible 
value  if  there  was  an  equal  number  of  observatories, 
where  observations  had  been  made  at  the  com- 
mencement of  the  period  of  twenty-five  years,  and 
which  afterwards  discontinued  the  same,  to  the  num- 
ber of  observatories  established  during  the  second 
period  of  the  above  mentioned  era.  This,  also,  is 
not  the  case.  The  majority  of  the  observatories 
have  been  recently  established,  and  this  would  give 
greatest  weight  to  the  argument  above  referred  to. 

Now,  then,  what  influence  could  such  cause  of 
error  have  in  the  results  shown  by  column  ten  ? 

As  may  be  seen  afterwards  (column  twenty- 
three)  the  tendency  to  an  increase  of  rainfall  during 
the  last  period  of  five  years,  in  relation  to  the  pre- 
ceding period,  is  very  remarkable,  and  for  that 
reason  the  influence  of  such  cause  of  error  would 


RAINFALL         IN          MEXICO 

serve  to  increase  the  plus  marks  in  column  ten,  because 
seven  out  of  the  twelve  plus  marks  appearing  in  the 
latter  column  refer  to  registers  carried  during  less 
than  ten  years  in  the  two  last  periods  of  five  years 
each,  therefore,  the  plus  would  perhaps  become 
minus  marks  if  the  observation  had  reference  to 
another  era.  The  error  that  might  have  been  com- 
mitted in  speaking  of  the  whole  era  of  1877  to  1901, 
with  the  data  on  hand,  is,  therefore  that  of  obtaining 
a  lesser  difference  than  the  real  one,  between  the 
less  and  plus  marks,  and  while  this  may  be  so,  the 
above  mentioned  objection  is  superseded  and  the 
conclusion  appears  well  founded. 

In  columns  eleven  and  twelve  I  have  marked 
the  number  of  years  under  the  normal  precipitation 
of  the  whole  era,  as  had  in  the  first  and  second 
periods,  for  each  observatory,  and  the  result  of  the 
comparison  corroborates  the  figures  of  column  ten, 
since  in  the  second  periods  there  have  been  137 
years  under  normal  conditions  against  115  had  in 
the  first  periods. 

Right  afterwards  I  have  divided  the  total  era 
under  consideration  in  five  periods  of  five  years 
each ;  I  have  calculated  the  averages  of  precipita- 
tion in  each  one  of  them,  showing  the  number  of 
years  taken  as  a  basis  of  calculation,  to  the  end  of 
discovering  their  correctness  as  an  average ;  I  have 
prepared  a  column  for  data  prior  to  1877,  and  the 
comparison  between  the  various  columns,  from  num- 
bers thirteen  to  twenty-five,  enables  us  to  study  if 

73 


RAINFALL         IN         MEXICO 

the  tendencies  of  rainfall  towards  increasing  or 
decreasing  have  been  more  apparent  at  any  given 
epochs. 


RAINFALL         IN         MEXICO 

Recapitulation 

First.  There  has  been  a  decrease  of  rainfall 
in  Mexico  during  the  last  twenty-five  years.  (Col- 
umns ten,  eleven  and  twelve  of  the  Chart). 

This  statement,  which,  in  the  opinion  of  many 
persons  who  believed  in  the  decrease,  may  appear 
as  a  fact  which  does  not  require  corroboration,  since 
it  was  well  known,  should,  however,  be  considered 
by  our  farmers  not  as  a  source  of  despair,  but,  on 
the  contrary,  as  an  encouragement  to  improve  agri- 
cultural systems,  to  prevent  the  reckless  felling  of 
forests,  and  to  reduce  the  burden  of  live  stock  from 
grazing  lands ;  to  promote  all  kinds  of  works  that 
will  cause  the  soil  to  absorb  a  greater  amount  of 
rain  water,  and  to  make  provision  for  the  collection 
of  such  water,  as  well  as  that  from  creeks  and  rivers. 
The  above  statement  should  also  impress  the  idea 
upon  the  mind  of  our  authorities  that  the  latter1 
works  and  improvements  ought  to  be  encouraged  as 
much  as  possible,  it  being  a  matter  of  vital  necessity 
to  do  so,  as  any  efforts  made  at  an  early  date  will 
facilitate  the  work  and  enhance  its  usefulness. 

Second.  The  decrease  in  rainfall  has  not  been 
so  general  as  has  been  claimed,  nor  even  regular 
during  the  period  from  1877  to  1901.  Pluviometric 
registers,  during  the  years  recorded,  show  an  in- 
crease in  Zapotlan,  Linares,  Aguascalientes,  Jalapa, 
Morelia,  Oaxaca,  Huejutla,  Pabelldn,  Me'rida,  Mon- 
terrey, Pachuca,  and  Guadalajara. 


RAINFALL          IN          MEXICO 

Between  the  first  five  years  (1877  to  1881)  and 
the  second  five  years  (1882  to  1886)  we  dare  say 
there  was  an  insignificant  decrease  (column  1 7 : 
ii-8+).  From  the  second  five  years  (1882  to 
1886)  to  the  third  five  years  (1887  to  1891)  there 
occurred  an  increase  also  insignificant  (column  19  : 
10-13+).  From  the  third  period  (1887  to  1891) 
to  the  fourth  period  (1892  to  1896)  there  was  a  gen- 
eral decrease  in  the  rainfall  (column  21  :  18-4+). 

From  the  fourth  period  (1892  to  1896)  to  the 
fifth  and  last  period  (1897  to  1901)  there  was  a 
very  remarkable  general  increase  in  our  rainfall 
(column  23  :  4-22+). 

The  results  shown  in  columns  twenty-one  and 
twenty-three  confirm  the  majority  of  the  remarks  I 
made  while  preparing  the  diagram  of  precipitation. 
The  above  mentioned  decrease  subsequent  to  1891 
and  increase  after  1896,  is  but  the  result  of  the  falls 
in  the  form  of  a  swing  I  remarked  in  making  up  the 
diagram,  which  falls,  though  failing  to  coincide  in 
the  same  years  in  the  different  localities  mentioned, 
do  appear  wtth  some  frequency  in  the  latter  part  of 
many  of  the  lines  of  precipitation. 

Third.  The  cause  of  the  decrease  of  rainfall 
during  the  period  studied  must  have  been  foreign  to 
the  action  of  men,  because,  should  the  cause  be  one 
of  those  generally  claimed  (development  of  railway 
system,  felling  of  the  forests)  the  effects  would  have 
increased  and  would  have  become  more  noticeable 
in  proportion  to  the  causes  originating  the  same. 
76 


RAINFALL          IN          MEXICO 

We  never  before  had  as  many  railroads  or  destroyed 
as  many  forests  as  we  have  in  the  last  five  years, 
and,  notwithstanding  that,  the  latter  period,  as  com- 
pared with  the  one  preceding  it,  shows  an  increase 
of  rainfall  in  twenty-two  cases  out  of  four  where 
there  has  been  a  decrease. 

The  falling  of  our  forests  may  have  some  influ- 
ence in  modifying  our  climate,  and  perhaps  the 
change  will  be  more  marked  in  the  future  than  it 
has  been  in  the  past,  but  it  is  not  the  principal 
cause  of  the  changes  claimed  by  public  opinion. 

The  injurious  influences  from  the  reckless  fell- 
ing of  the  forests  have  been  more  instrumental  in 
causing  the  disappearance  of  springs,  especially  in 
the  mountain  districts,  than  in  the  modification  of 
our  system  of  rainfall. 

The  magnitude  and  universality  of  the  decrease 
attributed  to  our  rainfall,  and  the  increase  of  its 
irregularity,  have  been  exaggerated  in  the  public 
mind,  there  being  three  general  causes  which  prin- 
cipally affect  the  case  :  The  greater  facility  one  has 
to  remember  and  appreciate  exceptionally  bad  years 
than  to  remember  and  appreciate  those  which  hap- 
pen to  be  exceptionally  good ;  the  opening  of  new 
waterworks  required  by  an  increase  of  cultivation  of 
irrigated  land  in  preference  to  those  depending  on 
rainfall,  and  the  scarcity  of  manual  labor  for  agri- 
cultural purposes  (first  part  of  this  study). 

The  increase  of  rainfall  in  the  last  period  of 
five  years  (column  23)  is  really  encouraging,  and  it 

77 


RAINFALL          IN          MEXICO 

would  be  more  so  if  we  did  not  have  to  record  the 
general  result  shown  by  column  ten,  and  so  stated 
in  the  first  part  of  the  recapitulation. 

There  has  been,  lately,  some  tendency  of  in- 
crease in  our  rainfall,  some  localities  have  had  in 
the  last  years  rains  which  surpass  the  amount  cal- 
culated as  normal,  but  we  have  not  sufficient  data 
to  support  a  general  prediction. 

There  are  a  few  cities,  as  may  be  seen  from  the 
diagrams  I  have  prepared,  whose  lines  of  precipita- 
tion rise  during  one,  two  or  three  years,  but  only  to 
come  down  again  during  similar  lapse  of  time.  I  be- 
lieve that  in  such  places,  considering  the  character  of 
the  curve,  bad  years  are  to  occur  after  a  series  of  two 
or  three  years  of  heavy  precipitation,  as  they  gener- 
ally alternate  one  another  in  series  of  short  duration. 

There  are  other  localities  where  great  falls  of 
the  line  precipitation  occur,  during  a  long  series  of 
years,  as  has  been  noted  in  the  proper  diagrams. 
In  such  places  the  continuance  of  a  series  of  years 
slightly  over  the  normal  elevation,  or  any  indication 
to  drop  in  the  curve  of  precipitation  must  be  a  cause 
of  alarm,  while  the  contrary  must  be  received  with 
marks  of  gratification  and  confidence.  It  is  the 
widely  repeated  prophecy  of  Joseph  on  account  of 
the  dreams  of  the  King  of  Egypt. 

Fifth.     In  order  to  provide  for  our  future  in 
this  respect,  whatever  the  same  might  be,  we  should 
endeavor  to  unite  the  efforts  of  administrative  action 
with  those  of  private  individuals  and  farmers. 
78 


RAINFALL          IN          MEXICO 

Confining  myself  to  the  latter  point,  recom- 
mendation should  be  made  in  the  first  place  to 
create  partial  pools  and  jetties  to  control  the  drain- 
age of  rainfall  and  thus  increase  the  absorption  of 
the  latter ;  the  construction  of  all  classes  of  works 
for  the  purpose  of  collecting  water  should  be  en- 
couraged ;  a  sensible  proportion  between  the  num- 
ber of  live  stock  and  the  surface  of  grazing  lands 
should  be  maintained ;  we  should  make  a  study  of 
and  endeavor  to  diffuse  our  useful  wild  plants, 
which  are,  without  doubt,  the  ones  which  can  better 
prosper  under  the  conditions  of  our  climate  and 
soil ;  we  ought  to  better  the  elements  of  our  natural 
prairies ;  to  build  watering  places  for  stock  in  the 
respective  farms  in  order  that  the  former  may  not 
have  to  travel  long  distances  in  search  of  food, 
destroying  pastures  where  the  soil  is  more  or  less 
sandy,  and  forming  footpaths  which  turn  in  creeks 
and  facilitate  the  drainage  of  rain  water ;  a  sensible 
felling  of  the  forests  and  the  use  of  improved 
methods  of  cultivating  will  help  to  bring  about  an 
economy  of  water. 

If  man  has  not  been  given  the  power  to  modify, 
so  far,  the  climate,  causing  the  increase  of  rainfall, 
he  can,  at  least,  make  better  use  of  the  small  quan- 
tity of  water  at  his  disposal  and  help  nature  imitat- 
ing it,  to  the  end  that  rainwater  may  be  absorbed, 
retained,  evaporated,  and  utilized  upon  the  soil 
instead  of  letting  it  run  into  the  sea. 


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